The present invention relates to methods and devices which make it possible to obtain threads by casting in a liquid. Such threads are, for instance, metal threads, particularly threads of amorphous alloys.
It is known to produce amorphous threads by projecting a jet of molten alloy into a liquid cooling layer, for instance a layer of water, applied by centrifugal force against the inner wall of a rotary drum. Such methods are described, for instance, in U.S. Pat. Nos. 3,845,805, 4,523,626 and French Patent 2 636 552. The Japanese Patent Application published under No. 63-137550 describes such a method in which use is made of devices at the end of the drum in order to separate a given number of layers of threads. The thread is extracted upon the stopping of the drum, so that this method cannot be used in continuous operation.
In order that a method of centrifugal casting in a drum can be used in continuous operation, it is necessary to have the thread emerge from the drum as it is formed. Various methods have been described for this purpose. It has been proposed, for instance, to use magnetic devices in order to apply the thread against a coil arranged outside the cooling liquid, these devices possibly furthermore employing a radially moving lever which is driven by the drum. Such methods are described, for instance, in U.S. Pat. No. 4,617,983, in the Japanese Patent Application published under No. 62-89526, and in the international application published under No. WO 87/155. These devices are complicated to use and may lead to instabilities of the film of water which are prejudicial to the continuity of the thread. Water and thread evacuation devices have been described, for instance, in the Japanese Patent Applications published under Nos. 60-61147, 60-76255, 60-166147, and 61-253147. These devices are also complicated to use and, furthermore, they raise sealing problems which are difficult to solve.